Most new laptop computers have a USB port instead of a RS-232
port. I've been doing some homework on these converters and find some
don't do a good job if good control of the handshaking lines are needed.
Does anyone have any personal experience with a converter that works
well for this use? The data rate is 19.2 Kbps now, but I can see that
going to 57.6 Kbps sometime this year. Thanks for any help.

I have several Macintoshes, and used Belkin converters at first. They
worked well, until Belkin didn't keep up their support for the system
10 software. The latest software was not supported at all, so I shopped
around and switched to a converter made by Keyspan (USA-19HS). There's
no looking back - it's been great.

We had some PC software problems with Belkin units which always seemed
to allocate themselves to exotic COM port numbers. Then the COM port
number reported by the driver did not match the port number found by our
software.

My Prolific based chip would not do handshaking properly. I tried every
driver combination I could find. It worked Ok for data coming in from my
Deluo GPS "mouse" but failed to let me program my JKMicro board or program a
device at work so I switched to IOGear and bought it at Fry's.

Had tremendous problems, until I inserted a delay in my application software
that ensured the buffer would fill at the baud rate. If I didn't control the
speed even if the software was set to the correct baud rate, windows would
transfer the data to the converter at max speed causing buffer overruns and
thereby loss of data

I'm also looking into adding USB to my design. I would like to try two
things:

1) That my embedded system emulates as a Memory stick. So that by
plugging in my device, i can copy some files from the filesystem to
the PC.

or

2) That my embedded system contains a USB host, so could plug in a
memory stick, transfer files to it. My system will be a 8 or 16
bitter, so not to much processing power or OS. Is there a kind of easy
to use hardware host on the market?

There may be by now, but odds are it's not worth having. It'll cost
you more in terms of hardware and power requirements than it's worth,
unless your embedded system is already untypically bulky.

USB is designed explicitly under the assumption of powerful host
computer controlling simplistic slave devices. The longer you look at
it, the more it tends to feel as if USB were part of a hidden plot by
Intel meant to ensure that a full-scale PC stays at the center of
everybody's "digital home".

I.e. if you don't plan on building most of a PC, or at least a
PocketPC, hosting USB is not really an option.

--
Hans-Bernhard Broeker ( snipped-for-privacy@physik.rwth-aachen.de)
Even if all the snow were burnt, ashes would remain.